Engineering Aramid Aerogel Fibers with Core‐Shell Structure for High‐Performance Thermal Protective Textiles

Abstract Overcoming the trade‐off between thermal protection and mechanical strength in aerogel fibers represents a significant challenge. To address this, it has structurally engineered aramid aerogel fibers (SEAAFs) with a hierarchical core‐shell structure through a two‐step coagulation treatment in wet‐spinning. The treatment involves the rapid gelation of aramid nanofiber (ANF) spinning sol precursor in acid, forming a rigid and highly ordered shell, followed by a slower gelation process in water, which results in an amorphous and porous core. This structural design enhances the mechanical robustness and preserves high porosity of SEAAFs, properties that can be further optimized by adjusting key spinning parameters, including the type and concentration of acid used, as well as the ANF precursor concentration. Upon optimization, SEAAFs achieve a high stress at break of up to 64.3 MPa and an ultralow thermal conductivity of 28.3 mW m ⁻¹ K ⁻¹ . The excellent mechanical property then enables the successful fabrication of a SEAAF fabric demo with a dimension of 1 × 0.2 m ( l × w ) on an automatic rapier loom. Moreover, the 0.8 mm‐thick aerogel fabric demonstrates excellent thermal insulation performance, comparable to significantly thicker conventional insulating materials under both high temperature (200 °C) and low temperature (−15 °C) conditions.